Plug tap



L. LUDWIG 2,446,709

PLUG TAP Aug. 10, 1948.

2 Sheets-Sheet 1 Filed April 18, 1944 W 4 III 1m];

1NVENT 0R.

ATTORN') Aug. 10, 1948. LUDWlG I 2,446,709

PLUG TAP Filed April 18, 1944 2 Sheets-Sheet 2 3/ 74 l I 64 a w 1 E {i K i i ,;i '30 Q- 1' a 4 INVENTQR. BY z M f M Patented Aug. 10, 1948 UNITED STATES PATENT OFFICE PLUG TAP Louis Ludwig, New York, N. Y.

Application April 18, 1944, Serial No. 531,622

2 Claims. (01. 173-334) This invention relates generally to electrical connection plugs, and more particularly to electrical connection plugs of a plural tap character in which the plug tap includes prong members adapted to engage a female electrical outlet and contact members associated with a plurality of female receptacles.

Among the objects of the present invention lies the provision of electric plug tap structure which is quickly and easily assembled in the course of the manufacture thereof to form a substantially permanent assembly.

The substantially permanent assembly of the present plug tap is advantageous for a number of reasons, among which are: The fact that the tap presents no exposed metallic parts, so that appearance is enhanced and shock liability isreduced to a minimum; the plug tap may not be disassembled by improper manipulation or by Vibration; and, dangerous improper use of the plug is avoided since in normal use it is substantially impossible to make wire-end contacts with the internal contact members of the plug tap, except through openings provided for the purpose, but not by separating the plug body halves.

By virture of the fact that the structure which secures the body members together is completely concealed, the external characteristics of the body members may be fabricated from the point of esthetic appearance and receptacle opening location independently of other structural considerations.

A feature of the present invention lies in the arrangement of the female receptacle openings so that they may lie in a. plane substantially perpendicular to the major flat surfaces of the prong members. This enables the use of a plurality of cube taps in a standard wall outlet so that each of the three receptacles or outlets in each of the cube taps may be utilized.

A further object of the present invention lies in the provision of a cube tap having the foregoing described advantageous characteristics and yet which uses a minimum amount of metal components. As will appear more fully hereinbelow, the contact members have the conducting tabs thereof formed from one piece of material instead of a plurality of pieces, as in conventional construction, and furthermore these conducting tabs do not have the terminals thereof bent over upon themselves as in prior constructions. In the improved construction herein disclosed, the conducting tabs of the contact member are rested against adjacent surfaces of the inside walls of the body member, so that a pressure contact is efiected in coaction with the conventional prong members of known attachment plugs (not shown) and this pressure contact may have a long efiective period of usefulness.

.A still further object of the present invention lies in the provision of a'cube tap of the character described wherein by virtue of the novel form, arrangement and coaction of the parts, economies in manufacture are accomplished With a resultant low cost and wide use.

These objects and other incidental ends and advantages will more fully appear in the progress of this disclosure and bepointed out in the appended claims.

In the drawings, similar reference characters designate corresponding parts throughout the several views of this embodiment.

Figure 1 is a rear elevational view of an electrical plug tap showing an embodiment of my invention.

Figure 2 is a sectional view as seen from the plane 2--2 on Figure 1.

Figure 3 is a sectional view partly in elevation as seen from the plane 33 on Figure 2.

Figure 4 is a front elevational View of the plug tap shown in Figure l, as seen from the rear of Figure 1.

Figure 5 is a sectional view of the plug tap as seen from the plane 5-5 of Figure 2.

Figure 6 is a sectional view as seen from the plane B-Bon Figure 2.

Figure '7 is a sectional view as seen from the plane 1--! on Figure 2.

Figure 8 is a view in perspective, showing the contact elements in the positions they occupy in the assembled plug with the body members and fastening or securing element removed.

In. accordance with the invention the plug tap generally indicated by reference character ID includes a pair of juxtaposed body elements H and It, a pair of juxtaposed contact elements [3 and M, a fastening. or securing element l5 and a spacer element IS. The. contact elements l3 and [4 are maintained in operative positions by being nested within the body elements, the latter being interconnected by the fastening element I5, and the prong members 11 and I 8 are maintained iln proper spatial relation by the spacer element The body elements I l and I2 are of substanv tially identical construction so that they may be fabricated in the same mold. The body elements H and I2 may thus have rear walls I 9 and 20, front walls 2| and 22, top walls 23 and 24, bottom walls. 25 and 26 and side walls 21 and 28. Each to say, inwardly of the outermost surfaces of the 7 band or flange an. The band so may be said to' have upper and lower walls 33 and 34 respectively and these walls preferably merge into the outer surface of the band 30 which is substantially at right angles thereto by curving the intersections of said surfaces.

The distance between the up,-

sitioned on the cross bar of the T. The contact members 59 and 60, therefore, have front contact tabs 61 and 68, side contact tabs 69, 10, 1| and 12, and inner contact tabs 13 and 14. The contact tabs 13 and 14 are provided with orifices of suitable size and shape so that they may be penetrated by the deformable ears 63 and 64, the latter being swaged over to rivet the contact members to the prong members. By virtue of the rectangular configuration of the orifices in the tabs 13 and 14 the contact members 59 and 69 are pre- -vented from rotating about the deformable ears "63 and 64 in planes parallel to the outer longitu- ."dinal surfaces of the projections 6| and 62. Each of thetabs 61-12 inclusive, is inwardly bent as best seen in Fig. 8 so that when the prongs of the attachment plug with which the tap In is used are inserted into any of the pairs of orifices per wall 33 and the lower wall 34 is substantially equal to or slightly less than the distance between the prongs of attachment plugs normally used with the device, said plugs not being shown. While the bands 3| and 32 are shown as extending outwardly from the outer surfaces of the front walls 2I-22, the rear walls I9-29, and the side walls 21-28, this is for the purpose of enhancing the external appearance of the device and making it easier to grasp for insertion or removal from a standard outlet.

Thus the bands 30, 3| and 32 are formed by peripherally extending, projecting flange portions 35 to 52, inclusive.

Located next to the band. 30 at the upper and lower walls are three pairs of orifices, which are positioned to correspond to the respective positions of the contact members of the contact elements as will more fully appear. Since the walls 33 and 34 are separated from each other by a distance substantially equal to or slightly less than the distance between the prongs on a standard attachment plug (not shown), merely straddling the band 30 by such attachment plug, the prongs thereof may be slid around the tap ID in any direction until the tips of the prong-s of the attachment plug coincide with any one of the three pairs of orifices 53-58, whereupon they may be directly inserted therein to make electrical contact with the contact members on the contact elements. The band 30 serves ,as an annular guide so that the prongs of the attachment plug may be tactually guided into place. Since there are no exposed electrically contacting parts on the tap ID, the last mentioned operation may be performed in the dark with considerable facility and no danger.

Turning now to a description of the contact elements generally indicated by reference characters l3 and I4 and perhaps best seen in Fig. 8, the said contact elements are substantially identical so that detailed description of one will suffice for the other. Thus, the contact elements l3 and M include the prong members 11 and I 8, and contact members 59 and 60. The prong members are of elongated shape preferably having tapered inner ends and laterally extending projections 61 and 62. The projections 61 and 62 have the iongitudinal surfaces thereof parallel to the axes of the respective prong members and are provided with integral deformable cars, 63 and 64. The upper ends 65 and 66 of the projections BI and 62 are adapted to and support the lower or inner surface of the spacer element 16 when the tap ID is in assembled condition. The contact members 59 and 60' are of generally T-shaped configuration with a fourth tab eccentrically po- 53-58, the tips of the prongs on the attachment plug pass outwardly of the tabs 61-12 as the case may be and make contact with the outer surfaces 15-16 of'the contact members 59 and 60. The inner surfaces of the body elements II and 12 at those points where the ends of the contact tabs 61-12 will be located in the assembled plug tap 19, are provided with inwardly directed ledges, 11-82. These ledges not only serve to strengthen the body elements II and I2 since they act as reinforcing struts, but also support the tips of the contact tabs 61-12 so that when the prong members of an attachment plug (not shown) engage the outer surfaces of the contact tabs, said tabs have their bent ends flexed. This last described action not only provides a better electrical contact between the contact tabs and the prongs, but also prevents the contact members 59 and 60 from being undesirably distorted. Furthermore, undue stresses are not transmitted to the connection between the tabs 13 and 14 and the deformable ears 63 and 64 on the respective prong members I1 and I8.

It may be noted in connection with the construction of the contact members 59 and 69 just described, that by virtue of the fact that they are each in one piecathe electrical resistance thereof is reduced and is more likely to remain constant than in the case of assembled groups of contact tabs. Furthermore, each of the contact members may be assembled to its respective pron member by only a single operation. This results in a more efficient and lower cost construction for the completed contactelements.

While the contact tabs 61-12 are shown as relatively smooth and curved, they may, of course, in accordance with well known practice, be pro vided with small projections which are adapted to have a snap action with the usual orifices in the prongs of the attachment plugs (not shown).

The two body elements H and I2 are maintained in proper position by the fastening. and securing element 15, which is in the form of an elongated pin or rod having a roughened surface. I have found that the fastening element I5 is preferably formed by a short length of threaded rod which is preferably provided with 30 threads per inch and in which the ends 83 and 84 tapered. The inner opposed surfaces of the body elements II and I2 are provided with inwardly extending juxtaposed cylindrical bosses having tapered entrances 81 and 88 which lead into the internal bores of said bosses which areof'an effective diameter less than the effective diameter of the securing element I5. I have found that the convergence of the entrances 81-88 is preferably 30 from the axis and that the effective diameter of the element 55 should exceed the effective diameter of the bores in the bosses 85, 85 by approximately .005 inch. By virtue of the fact that the element 45 is completely enclosed in the finished plug tap, it is not externally visible and therefore, the symmetry of the tap is not affected by the eccentricity of positionin thereof with respect to the body elements II and I2. Another advantage which flows from this construction, moreover, is that the prong members H and I8 may be extended into the plug body a greater distance with a resultant increase in strength and security of the contact elements 13 and 14. A still further advantage which results from the present construction is that the element l5 cannot be reached from the outside of the tap I 0 and so the tap cannot be disassembled in order to make direct wire connections to the contact elements I3 and M which would result in a hazardous operation of the plug tap and forbidden by the underwriters.

For the purpose of clarity in the present disclosure, one manner of assembling the plug is herewith given. The body member l2, let us say, may be placed upon a level surface. Thi may be visualized more easily if Fig. 2 is rotated through 90 so that the body element 12 is lowermost. Next the contact element 14 is placed within the body member I2. Following this, the spacer element 16, which is of H shape (see Fig. 1) is placed so that the legs 90 straddle the prong member l8. The spacer will be supported in an upright position thereat by reason of the fact that it stands between the inner surface of the rear wall and the projection 52. Following this, the contact element I3 is placed in position with the prong member ll disposed between the legs 9! of the spacer l6. Meanwhile, the contact tabs will be engaged by their corresponding ledges, as previously described. The element 15 is inserted under pressure into the boss 85 at any stage in the assembly. Finally, the body element II is placed so that the then exposed contact tabs may seat themselves therein and so that the then upper terminal 83 of the element I5 may enter the taper entrance 81. Pressure is then exerted axially of the element I5 and the two body elements H and I2 are brought into closed position. The pressure produces a wedging action between the element [5 and the internal bores of the bosses 85 and 86, which securely locks the two body elements I i and 12 together.

It may thus be seen that I have provided a novel and useful plug tap commonly referred to as a cube tap, and which presents a symmetrical and clean appearance on the external surfaces thereof. Danger of shock or improper use is practically eliminated. Each of the sets of orifices associated with the contact tabs is accessible even when a plurality of plug taps are disposed next to each other in the standard plural wall receptacles. My improved plug tap is very convenient in use because the peripheral band acts as a locating medium to properly position the prongs on an attachment plug for insertion therein The novel spacer element and its co-ordination with the body elements, permits the body elements to be closed with relation to each other from the fiat sides of the prong members I l and H3. The spacer element not only positions the prong elements with relation to each other, but is also itself positioned with respect to the prong elements or body elements by the action of the other elements. Furthermore, the spacer acts as a closure to prevent entrance of foreign objects through the space between the prong elements.

By virtue of the eccentricity of the interconnection of the body elements, the prong members may connect with the contact members at the inner surfaces of the latter, with a consequently reduced size and weight of the prong members.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

I claim:

1. In an electrical plug tap construction adapted to receive the prongs of a standard plug member in electrical attachment thereto, the combination Of a main body having four contiguous walls angularly disposed with respect to each other, a pair of prongs extending from one Wall thereof, a pair of laterally spaced prong receiving openings in each of the other three walls, said pairs of openings being in alignment, a continuous unbroken ridge raised above the outer surfaces of said three walls and disposed between the openings of all of said pairs of prong receiving openings, the Width of said ridge being slightly less than the distance between the prongs of such standard plug member, whereby once the prongs of said plug member are positioned so as to straddle the said raised ridge they may be slidably guided therealong to facilitate insertion into the next pair of prong receiving openings to be reached.

2. In an electrical plug tap construction a pair of elements, each comprising a substantially flat prong member, and a contact member, said contact member comprising a one piece substantially flat main body portion of generally T-shaped configuration and a tab integral with and in the same plane as said main body portion, said tab being eccentrically positioned on the cross bar of the T and xtending in the opposite direction from the third leg of the T, and means for fastening said prong member to said tab whereby the plane of said prong member is substantially at right angles to the plane of said contact member.

LOUIS LUDWIG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number 

